Hydraulic shuttle vavle for fuel injection pumps

ABSTRACT

The output of a fuel injection pump plunger is alternately directed to a pair of injection nozzles by a hydraulically actuated shuttle valve. A shuttle housing incorporated into the high pressure circuit includes a bore containing the valve shuttle which is reciprocated by alternating fuel pressure introduced at each end of the bore. The alternating pressurized fuel is supplied to the bore in timed relationship with the reciprocation of the pump&#39;&#39;s plunger by a rotary distributor driven by the pump cam shaft. Means are provided in the shuttle to interconnect the shuttle actuating and the injection pump high pressure passages during the intervals between fuel injection to establish a controlled low pressure level in the high pressure passages prior to the next injection.

'[ 1 July 10,1973

Primary Examiner-Laurence M. Goodridge Assistant Examiner-Cort R. FlintAnorneyl lowson and Howson [57] ABSTRACT The output of a fuel injectionpump plunger is alternately directed to a pair of injection nozzles by ahydraulically actuated shuttle valve. A shuttle housing incorporatedinto the high pressure circuit includes a bore containing the valveshuttle which is reciprocated by alternating fuel pressure introduced ateach end of the bore. The alternating pressurized fuel is supplied tothe bore in timed relationship with the reciprocation of the pumpsplunger by a rotary distributor driven by the pump cam shaft. Meansareprovided in the shuttle to interconnect the shuttle actuating and theinjection pump high pressure passages during the intervals between fuelinjection to establish a controlled low pres- INJECTION PUMPS Inventors:James R. Voss, Wilbraham; A.

Frank Jeney, Westfield, both of Mass. 1 v Assignee: AMBAC Industries,Inc., Springfield, 11]. Jan. 24, 1972 123/139 AM, 123/139 AL F02m 41/04123/139 R, 139 AL, 123/139 AM References Cited UNITED STATES PATENTSUmted States Patent 1 Voss et a1.

[ HYDRAULIC SHUTTLE VAVLE FOR FUEL [22] Filed:

211 Appl. No.: 220,203

[52] US. Cl.

[51] Int.

[58] Field of Search..................

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dn 0 kn C e m sm R LR w w 199w] /33 311 3 2 2 133 1 22 11 mm m m amm mmt H a "m n ms m amn-MO n.1..n ACPLC 540069 66552 99999 11111 Ill/l 689 724 77 0 65 3 3 3290 94522 1 2 3322'- 1 HYDRAULIC SHUTTLE VAVLE FOR FUELINJECTION PUMPS The present invention relates generally to fuelinjection equipment and relates more specifically to a hydraulic shuttlevalve for diesel fuel injection pumps which serves to alternately directthe output of a pumping plunger between two fuel injection nozzles.

The present invention is directed to the type of fuel injection systemwherein the injection nozzles are supplied with fuel which is pumped andmetered at a central fuel injection pump remote from the nozzles. Inthis type of system, the timing as well as the metering is .controlledby the pump, and the nozzles valve opens,

usually against spring pressure, only during the brief pumping intervalto admit the pumped fuel quantity to a combustion chamber. The fuel ispumped at extremely high pressures, commonly between 5,000 and 20,000psi, in order to effect the proper nozzle operation and fuelatomization. v

Fuel injection pumps of the category described enjoy commercialpopularity in three general types. In a first type, a separate singleplunger pump is provided for each combustion chamber. This type isparticularly adapted for use with large stationary diesels wherein thedistance between cylinders would preclude the use of a single centrallylocated pump with its fuel distribution conduits.

ln a second type of pump, a single pumping element actuated by amultilobed cam shaft is utilized to supply a plurality of enginecylinders by combining a distributor arrangement into the high pressurecircuit. Typically, the pumping plunger is rotated and reciprocated, andsuitable distributor slots in the rotating plunger direct the pumpoutput sequentially to the engine cylinders. The fuel metering functionis carried out by a fuel control sleeve on the plunger to selectivelyuncover a port communicating with the pumping chamber.

The third type of pump, and that to which the present invention isdirected, is characterized by a central pump unit from which fuel isdistributed through conduits to the individual .combustion chambers, andwherein a separate pumping plunger is provided for each engine cylinder,the plungers commonly being arranged in line and driven by a common camshaft. Fuel metering is accomplished by rotation of the plungers to varythe beginning or ending (or both) points of the plunger stroke utilizedfor high pressure pumping. This type of pump, while more expensive tobuild than the rotating distributor-plunger type pump described above,is recognized as a more dependable, longer lasting and generallysuperior pump and is preferred for engine fuel control where cost is notan overriding factor.

The present invention permits the utilization of the individual plungertype pump with only half the number of plungers required with theconventional installation. This is accomplished by alternately directingthe output of a given pumping plunger to one'or the other of two fuelinjection nozzles. The broad concept of dividing the output of a pumpingplunger is not new, as evidenced by the disclosure of U. S. Pat. No.1,720,657 wherein an attempt was made to mechanically link a spool valveto the pump drive shaft. It is not believed, however, that such a systemhas been successfully operated or would be commercially feasible in viewof the complexity of the mechanical linkage, the difficulty ofmaintaining small high pressure volumes, and the diffirocate the shuttlein timed relationship with the plunger pumping strokes. A fluid passagearrangement is provided within the shuttle for directing the pressurizedshuttle-actuating fuel into the idle fuel delivery passages. Similarly,passage means in the shuttle are provided to pressurize the fueldelivery conduit between the shuttle and the pump delivery valve as theshuttle passes over center. These arrangements serve to suppresscavitation erosion damage within the fuel passages and may permit theelimination of the fuel delivery valve by maintaining a constantlyfilled condition of the delivery passages. Further, by maintaining con-.

stantly filled high pressure lines at the beginning of injection, thestroke to stroke variation of fuel injection quantity and timing isreduced, with beneficial reduction in overall smoke and other exhaustpollutants. An added advantage of the latter passage arrangement is theprevention of damage to the system should the shuttle'happen to stopover center when the engine operation is interrupted;

It is accordingly a first object of the present invention to provide newand useful improvements in fuel injection equipment.

A further object of the invention is to provide an arrangement fordividing the output of a fuel injection pump plunger between two fuelinjection nozzles.

Another object of the invention is to provide apparatus as describedincluding means for maintaining a consistent pressurized condition ofthe idle fuel discharge passages throughout the operating range of theengine.

A still further object of the invention is to provide a hydraulicallyactuated shuttle valve for dividing the output of the fuel injectionpump plunger between two fuel injection nozzles.

A still further object of the invention is to provide apparatus asdescribed including means for maintaining a pressurized condition of thefuel delivery passage between the delivery valve and the shuttle valveduring the interval between plunger injection strokes v Still anotherobject of the invention is to provide a hydraulically actuated valve. asdescribed including means for preventing damage to the system uponstopping of the valve member in an over center position.

A still further object of the invention is to provide apparatus asdescribed which will provide substantial economies in the manufacture offuel injection pumps and which will provide a more compact pump byhalving the number of pumping plungers required for a given number ofengine cylinders.

Additional objects of the invention will be more readily apparent'fromthe following. detailed description of embodiments thereof when takentogether with the accompanying drawings wherein:

FIG. 1 is a schematic perspective view showing a fuel injection pumpembodying the present invention to permit a single pumping plunger toalternately direct fuel to one or the other of a pair of fuel injectionnozzles;

FIG. 2 is an end elevational view partly in section of a fuel injectionpump showing the supply pump and distributor embodying the presentinvention as schematically illustrated in FIG. 1;

FIG. 3 is a sectional view taken along line 33 of FIG. 2 showing theinterior details of the pump;

FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG. 3showing details of the hydraulic head including the shuttle valve;

FIG. 5 is a reduced scale view taken along line 5-5 of FIG. 2 andshowing the interior passages for the shuttle-actuating fuel;

FIG. 6 is a reduced view partly in section taken along line 6-6 of FIG.3 showing the fuel passages leading from the rotary distributor towardthe shuttle;

FIG. 7 is a greatly enlarged view of the distributor shuttle as shown inFIG. 4 with the shuttle positioned so as to direct a flow of injectedfuel through the right hand delivery passage',

FIG. 8 is a view similar to FIG. 7 with the shuttle positioned to directa flow of injected fuel through the left hand delivery passage;

FIG. 9 is a view similar to FIG. 7 but showing a modified form ofshuttle;

FIG. 10 is a view similar to FIG. 8 but showing the modified shuttle ofFIG. 9;

FIG. 11 is a view showing the shuttle of FIGS. 7 and 8 in an over centerposition;

FIG. 12 is a view similar to FIGS. 8 and10 showing a further modifiedform of shuttle;

FIG. 13 is a view similar to FIGS. 7 and 9 showing the modified form ofshuttle of FIG. 12 and FIG. 14 is a view similar to FIG. 11 showing thefurther modified form of shuttle of FIGS. 12 and 13 in an over centerposition.

Referring to the drawings and particularly the schematic view of FIG. 1,a single plunger fuel injection pump is illustrated embodying thepresent invention to alternately direct the pump output to a pair offuel injection nozzles 22 and 24. The nozzles, by means of the nozzleholders 22a and 24a, would be mounted so as to extend into thecombustion chambers of an internal combustion engine for the purpose ofintroducing an atomized spray of fuel in a quantity metered by the pumpin accurately timed relationship with the cylinder piston movements. Thenozzles are remotely located from the pump 20 and are connected theretoby the respective discharge conduits 22b and 24b as schematicallyillustrated in FIG. 1. The nozzles are of the type which open inresponse to an increase in pressure in the discharge conduits and closeupon the drop in pressure following delivery of a metered quantity offuel. Since the nozzles, nozzle holders and the discharge conduits areconventional in every respect, there is no need for a further detaileddescription thereof.

The pump 20 includes a plunger 26, the upper end of which extends intothe barrel 28 of the pump to effect a pumping of fuel therefrom in aconventional manner. The plunger 26 is driven in reciprocation by camlobes 30 on the pump cam shaft 32 which is coupled to the engine towhich the pumped fuel is delivered. A roller tappet 34 on the lower endof the plunger 26 bears against the cam lobes 30 and is maintained incontact with the cam surface at all times by the plunger spring 36. Thespring is seated at its upper end against the spring seat 40 fixedlymounted in the pump housing and the lower spring seat 42 on the plungeradjacent the tappet 34. As will be explained in more detail hereinafter,a controll sleeve 44 having a gear segment thereon and a downwardlydepending cylindrical portion 46 is rotatable by a control rack torotate the plunger and thereby control the metering of the 48 which areaxially slidable in slots 50 of the sleeve portion 46.

The pump structure described thus far is conventional. The presentinvention involves the novel arrangement for dividing the pump fueloutput between the injection nozzles in a reliable, synchronized mannerwhich will maintain a pressurized condition of the idle fuel deliveryand discharge conduits as well. In the embodiment illustrated, theinvention includes a shuttle housing 52 located above the delivery valveand adapted to receive the output of the pumping plunger 26 through afuel delivery passage 54. A horizontal shuttle bore 56 in the shuttlehousing contains the shuttle 58 which in a manner described hereinafterdirects the flow of fuel from the passage 54 alternately to thedistributor passages 60 or 62 which respectively connect by means ofunions 60a and 60b with the conduits 22b and 24b to carry the fuel tothe injection nozzles.

The shuttle 58 is reciprocated within the bore 56 by a hydraulic controlsystem. This system as shown schematically in FIG. 1, includes conduits64 and 66 opening into the ends of the bore 56, which conduits lead to adistributor generally designated 68. The distributor includes a camshaft driven distributing member in the form of a pump gear 140 havingpressurized fuel and drain chambers 162 and 164 respectively which areadapted to alternately communicate with the conduits 64 and 77 tothereby alternately supply pressurized fuel to the opposite ends of thebore 56. This produces a reciprocating movement of the shuttle 58 inaccurately timed relation with the plunger pumping strokes.

The above description of the schematic view of a pump embodying theinvention is provided to give a broad understanding of the structuralarrangement of a pump embodiment. For a detailed understanding of theinvention and particularly the arrangement for maintaining a pressurizedcondition of the idle fuel delivery and discharge passages, a detaileddescription of specific embodiments are provided herebelow.

Referring to FIGS. 2 and 3, the preferred embodiment illustrated thereinis accorded the same identifying numerals for corresponding parts as theschematic illustration of FIG. 1. The pump 20 is mounted within a pumphousing 76 having a central perpendicular bore 78 within'which theplunger 26 is mounted for reciprocation. Acam shaft compartment 80 inthe lower end of the housing 76 accommodates the cam shaft 32 which isjournaled therewithin. The compartment 80 is closed at the right handend of the pump as viewed in FIG. 3 by the cover plate 82 bolted to thehousing. Similarly, the opposite end of the compartment 80 is closed bythe cover plate 84 which includes an inwardly extending portion 86 onwhich are mounted the seals 88 for separating the lubricating oil in thecam shaft chamber from the fuel in the distributor and governor chamber.The shaft 32 is coupled directly to the engine supplied with fuel by thepump and is driven at half engine speed for a four cycle engine or atengine speed for a two cycle engine.

lower end of which is disposed within the upper end ofthe bore 78. Anupper portion 100 of the sleeve 98 is 4 accommodated by the enlargedbore 102 coaxial with bore 78. The upper end 104 of the sleeve 98 isflanged for securing to the upper end of the housing 76 by suitablemeans (not shown). I

A pumping chamber 106 is formed within the bore 94 of barrel 28 by thetop of the plunger 26 and the delivery valve holder 108 disposed withinthe sleeve 98 above the barrel28. A delivery valve 110 of conventionalconstruction is located within the valve holder 108 and serves to admitfuel to the delivery passage 54 of the shuttle housing 52 during thehigh pressure pumping portion of the plunger stroke. The shuttle housing52 is secured above the delivery valve holder 108 within the doublethreaded securing ring 112.

The means for rotating the plunger 26 to effect a nietering of the highpressure fuel output of the plunger includes a control rack 114extending horizontally through the housing 76 for connection with theengine governor. The rack 114 engages the teeth of the gear segment oncontrol sleeve 44 which rotates about a downwardly depending cylindricalportion 116 of the barrel 28. The cooperative elements of the plungerfor coupling the plunger for rotation with the control sleeve 44 areclearly shown in FIG. 3 and include the annular land 118 of the plungerfrom which the lugs 48 extend for sliding cooperation with the slots 50in the portion 46 of the control sleeve.

Referring to FIG. 4, an annulus 120 near the upper end of the plunger 26communicates with the pumping chamber 106 by means of a vertical slot122 in the plunger. The plunger is relieved above the annulus 120 andadjacent the slot 122 to form a helical shoulder 124 adapted tocooperate with a fuel spill port 126 in the barrel 28. A fill port 128in the barrel opposite the spill port 126 communicates as does the spillport with an fuel sump 130 formed between the outer sleeve 98 and thehousing bore 102. The fuel pump 130 is supplied with fuel under pressurefrom a fuel supply pump 138.

The fuel supply pump assembly 138 as best shown in FIG. 2 is a gear typeincluding a lower gear element 140 and a smaller upper gear element 132.The intermeshing teeth of the elements 140 and 142 pressurize fuelintroduced therebetween from fuel inlet 146, the high pressure fuelbeing passed into the fuel outlet 144. As shown in FIG. 3, the gearelement 140 is mounted and keyed on the stub shaft 148 which isjournaled within is driven by the splined connection of stub shaft 148with the cam shaft 32. The upper gear element 142 is secured to anddrives the governor shaft 158 which extends into the adjacent enginegovernor (not shown). Sandwiched between the fuel supply pump housing156 and the cover plate 84 is the distributor porting plate 160, thefunction of which will shortly become apparem.

The fuel supply pump 138 and specifically the gear element 140 thereofincorporates a distributor for the hydraulic actuation of theshuttle toalternately direct pressurized fuel to the fuel passages 64 and 66. Thedistributor includes an arcuate pressurized shuttle drive fueldistribution chamber 162 and a diametrically opposed arcuate shuttledrain chamber 164 in the gear element'140. The shuttle drive fueldistribution chamber 162 communicates at all times with a fuel supplyport 166 in the distribution plate 160 which by means of a passage 168in the plate 84 as shown in FIG. 6 connects with a passage 170 (FIG. 5)which joins with the fuel supply passage 171 as shown in FIGS. 4 and 5.A port '172 in the housing joins the passage 171 with the sump 130,which is supplied with pressurized fuel from'the fuel supply pump outlet146 by suitable housing passages (not shown); An annular groove 173 inthe gear element 140 passing outside the drain chamber 164 is located onthe same radiusas the supply port 166 and hence supplies the shuttledrive distribution chamber 162 with pressurized fuel at all times. Apassage 175 in the plate 84 supplies a flow of lubricating fuel'to thestub shaft 148.

The shuttle drain chamber 164 as shown in FIGS. 2, 3 and 6 communicateswith a drain port 176 in the distributor plate 160 which in turn opensinto the drain passage 177 in the cover "plate 84 from which fuel passesinto the housing sump through passage 178. An annular groove 180 in thegear element on the same radius as the drain port 176 keeps the drainchamber 164 in constant communication with the drain port 176. Annulargrooves 173 and 180 opposed from the grooves 173 and 180 are provided tobalance the fuel pressure forces on each side of the gear element 140.

The opposite ends of the shuttle housing bore 56 ar alternately suppliedwith pressurized fuel from the distribution chamber 162 and drained ofthe shuttle displaced fuel by communication with drain chamber 164 by alabyrinth of passages making up the fuel delivery passages 64 and 66 ofthe schematic FIG. 1. Considering first the passage 64 which in theposition illustrated both in the schematic view of FIG. 1 and thedetailed illustrations of FIG. 2-6' is in communication with the drainchamber 164, the passage comprises a port 64a in the distributor portingplate leading to the vertical passage 64b in the cover plate 84, this inturn opening into the passage 64c and 6411 in the housing side coverwhich through port 64e in the housing communicates with annulus 64f ofthe sleeve 98. A port 64g in the sleeve 98 leads from the annulus 64f toan annulus 64h in the delivery valve holder 108. A vertical passage 64:in the delivery valve holder alignswith a similar passage 64j in theshuttle housing which opens into an annulus 64k at one end of theshuttle bore56.

Similarly, the passage 66 connecting the distributor with the oppositeend of the shuttle housing plunger bore includes a port 66a in thedistributor porting plate; I

passage 66b in the coverplate 84. passage 66c in the housing, passage66d in the housing side cover plate,

port 66e in the housing, annulus 66f and port 66g in the sleeve 98, anannulus 66h between the sleeve 98 and the delivery valve holder,vertical passages 66i and 66] respectively in the delivery valve holderand shuttle housing, and the annulus 66k in one end of the shuttlehousing bore 56.

The shuttle drive fuel distribution chamber 162 and the drain chamber164 are arranged with diametrically opposed and radially aligned endsand the ports 64a and 66a are diametrically located with respect to thecenter of rotation of the gear element 140 with the result that theports 64a and 66a are simultaneously opened to communication with thefuel and drain chambers. Accordingly, when one end of the shuttlehousing bore 56 is opened to drain, the other end is supplied withpressurized fuel. For example, as illustrated in FIG. 2 with the gearelement 140 rotating in a clockwise direction, the port 66a is open tothe distribution chamber 162 so that pressurized fuel is delivered tothe annulus 66k through the ports and passages 66h-j. Simultaneously,the port 64a is open to the drain chamber 164 and the annulus 64kthrough ports and passages 64b-j has opened the opposite end of theshuttle housing bore to the drain sump. Since the fuel distributionchamber 162 and drain chamber 164 have the same arcuate extent, theports 64a and 66a will be simultaneously opened and closed to thepressurized fuel and drain chambers.

Referring to FIG. 4 and the enlarged views of FIGS. 7, 8 and 11, theshuttle valve assembly includes a generally cylindrical shuttle element182 having an axial bore 184 therein. The bore 184 includes a smallerdiameter portion 184a at the right end which opens into a largerdiameter portion 184b at the conical shoulder 186. The sleeve 188disposed within the larger bore portion 184k terminates inwardly in aconical end 190. A ball 192 is slidably disposed between the sleeve end190 and the shoulder 186 and is adapted to cooperate with the conicalsleeve end and shoulder to seal their respective circumscribed borepassages.

The outer surface of the shuttle element includes circumferentialgrooves 194 and 196 of substantial axial length adjacent the ends of theshuttle and a central intermediate circumferential groove 198 disposedtherebetween and divided therefrom by lands 200 and 202. Radial ports204 in the groove 198 provide communication between the groove and thebore 18% in the region traversed by the ball 192 between the ball limitpositions.

A snubbing arrangement is provided at each end of the shuttle housingbore 56 to prevent the destructive impact of the shuttle at the ends ofits strokes. The snubbing means includes inserts 206 and 208 securedwithin the bore 56 at the opposite ends thereof. Radial passages 210 and212 respectively in the inserts 206 and 208 communicate with the annuli'64k and 66k in the shuttle housing. Axailly inwardly directedcylindrical portions 214 and 216 of the inserts having passages 218 and220 therein respectively connect the passages 210 and 212 with theshuttle housing bore 56. The ends 222 and 224 of the shuttle elementrespectively include axial counterbores 226 and 228 which are adapted toreceive the portions 214 and 216 of the inserts 206 and 208. The fueltrapped between the inserts and shuttle ends radially outwardly of theportions 214 and 216 provides a damping effect preventing an undesirableimpact of the shuttle ends with the inserts at the end of each shuttlestroke.

For operation of the pump, the cam shaft 32 is connected to the engineto be supplied with fuel and the shaft 158 is connected to an adjacentgovernor in a conventional manner. The unions 60a and 60b are joined bylengths of. discharge tubing to the injection nozzles in the mannershown schematically in FIG. 1. The control rack 114 is connected to thegovernor to provide a metering control of the pump output.

During operation, the rotation of the cam shaft 32 and the cam lobes 30carried thereby provide reciprocating motion of the plunger 26, the camlobes through tappet 34 moving the plunger upwardly while the returnspring 36 serves to hold the tappet in engagement therewith and providedownward movement of the plunger. Fuel introduced into the inlet 146from a suitable source (not shown) is pressurized by the fuel supplypump 138 and is conducted from the pump outlet 144 to the fuel supplyannulus by internal housing passages (not shown). When the upper face ofthe plunger 26 opens the ports 126 and 128m the pumping chamber 106, thechamber as well as the annulus 120 and slot 122 are filled with fuel. Onthe upstroke of the plunger, the ports 126 and 128 are closed by theplunger and the fuel in the pumping chamber 106 is pumped through thedelivery valve 110 into the delivery passage 54. The fuel quantitydelivered is controlled by the rotational disposition of the plungersince the helical shoulder 124 determines the end of delivery by openingthe spill port 126, thus permitting fuel in the pumping chamber to drainthrough the slot 122 into the fuel sump 130. Upon opening of the spillport 126, the delivery valve 110 closes until reopened upon thesucceeding pumping stroke. The rotation of the plunger to effect themetering of the fuel is carried out by the governor through movement ofthe control rack 1 14 which rotates the control sleeve 44, the dependingportion 46 of which rotates the plunger lugs 48 engaged in the slots 50thereof. The arrangement of fuel pumping and metering control as brieflydescribed above is well known in the art and further description thereofis accordingly unnecessary.

The metered quantities of fuel injected by the plunger into the deliverypassage 54 are alternately directed into one or the other of thepassages 60 and 62 and hence into the injection nozzles 22 and 24 by theshuttle assembly 58. In the schematic view of FIG. 1 and in the views ofthe specific embodiment of FIGS. 2-8 and 9, the fuel pump gear elementis positioned to supply pressurized fuel through the ports and passages66a-k to the right-hand side of the shuttle bore 56 as most readily seenin FIG. 7. The introduction of pressurized fuel to the right-hand end ofthe shuttle bore moves the ball 192 to the left limit position withinthe shuttle element, the ball seating against the conical end of thesleeve 188 thereby sealing the passage within the sleeve. The shuttle isthen moved by the pressurized fuel to the left against the left-handinsert 206, the shuttle being snubbed by the trapped fuel outside of theportion 214 of the insert.

With the shuttle in the position shown in FIG. 7, the fuel injected bythe plunger passes through the passage 54 into the groove 196 of theshuttle element which is in communication with the passage 62 leading tothe nozzle 24. During the injection flow into passage 62, the passage 60is maintained filled with pressurized fuel fuel injection into thepassage 62 and conduit 24b serves to reduce cavitation erosion andimprove the uniformity of .injection.

Should the end of injection leave a high residual pressure instead ofthe cavities, communication between passage 60 and the shuttle groove198 serves as a pressure relief instead of fill. In either case, by thetime of the beginning of the next injection, the high pressure passageswill contain supply pressure.

Following the completion of injection to the nozzle 24, the rotation ofthe gear element 140 opens the ports and passages 66a,k to drain chamber164 and the ports and passages 64a-k to the pressurized fuel chamber162. The introduction of pressurized fuel through the insert 210 to theleft side of the shuttle housing bore 56 first moves the ball 192 to theright-hand limit position against shoulder 186 following which theshuttle element moves to the right-hand position shown in FIG. 8 againstthe insert 208, being snubbed thereagainst in the same manner describedabove with respect to the insert 206. As the shuttle element movesacross fuel delivery passage 54 as shown in FIG. 11, the annular groove198 communicates with the passage 54 and, by means of ports 204 and theshuttle bore, supplies pressurized fuel from the distributor to thedelivery passage. Accordingly, the delivery passage 54 in a mannersimilar to that described above with respect to the passage 60, ismaintained in a filled pressurized condition to minimize cavitationerosion and improve the injection uniformity.

Following movement of the shuttle to the right-hand position shown inFIG. 8, the fuel injected through the fuel delivery passage 54 passesinto the groove 194 of the shuttle which in this position communicateswith both the passage 54 and the passage 60 to deliver the fuel intopassage 60, the conduit 22b, and the nozzle 22. At the same time, theintermediate groove 198 of the shuttle, element is in communication withthe passage 62 and accordingly by means of ports 204 maintains apressurized condition of the passage 62 and conduit 24b to maintain afilled condition of the passage and conduit for the purpose describedabove.

In the event that the shuttle element should stop in a central positionsuch as that shown in FIG. 11, it is important that means be provided toprevent damage to the system should injection incur before the shuttleelement has been advanced to a limiting position against one of theshuttle housing bore inserts. Should injection occur with the shuttleelement in the position shown in FIG. 11, the injected fuel will enterthe intermediate shuttle groove 198, pass through the ports 204 into theshuttle bore, and thence through the ports and passages 64a-k to thedistributor 68 and ultimately the fuel supply pump 138. Since the fuelsupply pump is a positive displacement type pump, an output pressureregulator is necessary (not shown) and serves to relieve the otherwisedestructive pressure buildup which might occur upon dead heading" of theshuttle. It will be apparent that the width of the lands 200 and 202cannot exceed the diameter of the passage 54 since otherwise there wouldbe a possibility of one of the lands completely blocking the passage.

Should the engine start with the shuttle over center as in FIG. 11 andthe injection begin with the ball 192 at its opposite limit positionfrom that shown in FIG. 11, the injection will pass into the drain'sumpof the pump and will similarly not cause any damage to the pumpcomponents.

A modified embodiment of shuttle assembly is shown in FIGS. 9 and 10wherein the shuttle element 182' is v modified in certain respects, theshuttle housing passages, and the inserts at the end of the shuttlehousing bore 56 being identical with that of the above describedembodiment and hence bearing the same identifying numerals. The shuttleelement 182' is characterized by circumferential grooves 194' and 196'equivalent to and serving the same purpose as the grooves 194 and 196 ofthe shuttle element 182. However, instead of a single intermediatecircumferential groove, the shuttle element 182' includes a pair ofgrooves 240 and 242 intermediate the grooves 194' and 196' and which areseparated by a land 244. The element 182', instead of the through boreof the previous embodiment, includes a bore 246 extending partwaythereinto from the lefthand end of the element, and a bore 248 extendingthereinto from the right-hand end of the element. The bores 246 and 248are coaxial with the shuttle element for a length coextensive with theannular grooves 194' and 196. Bore extensions 246' and 248' respectivelyof the bores 246 and 248 extend in an offset, side by side relationRadial ports 250 in the groove 2 42'connect the groove with theboreextension 246' while ports 252 connect the groove 240 with the boreextension 248'.

The operation of the modified embodiment of FIGS. 9 and 10 is in effectthe same as that of the previously described embodiment, since thegrooves 240 and f242 will respectively align with the passages 60 and 62in the limit positions of the shuttle element shown in FIGS. 9 and 10.In the left-hand shuttle limit position of FIG. 9, the injected fuelfrom passage 54 passes through the groove 196' and into the passage 62while at the same time the pressurized fuel from the righthand end ofthe shuttle housing bore passes through bore 248, bore etension 248',ports 252 and groove 240 into the passage 60. When the pressure isreversed to the left-hand side of the shuttle housing bore, the shuttleelement is moved to the right-hand limit position-shown in FIG. 10whereupon the injected fuel passes from passage 54 through groove 194'into passage 60. Simultaneously, the pressurized fuel in the shuttlehousing bore passes through bore 246, bore extension 246', ports 250,groove 242 and into the passage 62 to maintain a minimal residualpressure therein. As the shuttle element 182' passes over center, itwill be evident that either the groove 240 or the groove 242 will bepressurized and will accordingly fill the idle delivery passage 54 withpressurizedfuel upon passage thereacross. The embodiment of FIGS. 9 and10 accordingly carries out the same functions as the precedingembodiment. I I

In FIGS. 12-14, a still further embodiment of the shuttle assembly isillustrated wherein the shuttle housing, including the shuttle housingbore, passages and inserts are identical with those shown in the twopreceding embodiments. The shuttle element 182" is considerably simplerthan the preceding embodiments and does not include any type of bore.The shuttle element 182" is a cylindrical member having a centralcircumferential groove 260 therein of sufficient axial extent tocommunicate with both the passages 60 and 62 when the shuttle is in anintermediate position such as shown in FIG. 14. Grooves 266 and 268adjacent the shuttle element ends are balancing grooves to assure auniform bearing of the element against the shuttle housing bore wall.

In the position shown in FIG. 12 wherein the shuttle element 182" isshown in its right-hand position, the injected fuel from passage 54passes around groove 260 and into the passage 62. Upon shifting of theshuttle element to the left-hand position as in FIG. 13 in response topressurization of the right-hand end of the shuttle housing bore, thefuel from passage 54 again passes around groove 260 over center as shownin FIG. 14, at least one and possibly both of the passages 60 and 62will communicate with the groove 260 and hence any injected fuel willpass into one or the other or both of the injection nozzles withoutdamaging the pump. The likelihood of the shuttle stopping over center isremote and should it happen, the injection of fuel into an enginecylinder out of phase will not impede the starting and operation of theengine.

By extending the stroke of the embodiment of FIGS. 12-14, the filling ofthe fuel discharge passages 60 and 62 by pressurized fuel betweeninjections can be realized. However, it is not possible to fill thedelivery passage 54 with pressurized fuel as is achieved by the previousembodiments. However, the shuttle of FIGS. 12-14 can be produced atconsiderably less expense than those of the two preceding embodimentsand for many applications may prove entirely satisfactory.

The desirability of maintaining a uniform residual pressure in the fueldelivery' passages downstream of the delivery valve is well established.The retraction volume type of delivery valve provides a sharp cutoff ofthe fuel injection by the nozzle but it may also result in the creationof bubbles as the line pressure is sharply reduced and a resultantcavitation erosion of the ports and passages when the high injectionpressures collapse the bubbles. By filling these passages with fuel atmodest pressure, the collapse of the cavitation bubbles is harmless.Also by pressurizing the delivery passages through the shuttle, theuniformity of injection is significantly improved since the residualpressure level is no longer dependent on the delivery valve operation. Ashuttle actuating pressure in the range of 50l00 psi has provensatisfactory for providing the necessary movement of the shuttle elementas well as the filling and pressurization of the delivery passages.

So effective is the shuttle for carrying out this function, that it ispossible to eliminate the delivery valve altogether in certain pumpembodiments and depend upon the shuttle to maintain the filled andpressurized condition of the fuel delivery passages and conduits.

It will be obvious that the present pump, although illustrated with onlya single pumping plunger, may include a plurality of plungers, alldriven by a common cam shaft. The distributor 68 can be adapted to servea number of shuttles simply by providing additional ports whichalternately communicate with the distributor fuel and drain chambers. Afour cylinder engine might accordingly be supplied with fuel from a twoplunger pump, while an eight cylinder engine could be equipped with afour plunger pump in accordance with the invention. The economies ofproviding the relatively simple shuttle in place of a separate pumpingplunger can be readily appreciated. Coupled with the describedfunctional advantages, the invention can be understood to represent asignificant advance in the fuel injection art.

Manifestly, changes in details of construction can be effected by thoseskilled in the art without departing from the spirit and scope'of theinvention.

We claim 1. In a fuel injection pump adapted to intermittently supplymetered quantities of high pressure fuel to a first fuel injectionnozzle, the improvement comprising means for alternately directing theintermittent fuel output of said pump into a second nozzle, said meanscomprising a hydraulic shuttle assembly including a shuttle housinghaving a bore therein, a shuttle element slidably disposed in said bore,a delivery passage in said housing for introducing the fuel output ofsaid pump into said shuttle housing bore, a pair of fuel dischargepassages in said shuttle housing communicating with a said housing bore,said discharge passages being adapted for connection to conduit meansfor delivering fuel to said first and second fuel injection nozzles,means for establishing limit positions of said slidable shuttle element,means on said shuttle element for providing fluid communication of saiddelivery passage with one of said discharge passages when said shuttleelement is in a first limit position in said bore and for providingfluid communication of said delivery passage with the other of saiddischarge pass ages when said shuttle element is in a second limitposition in said bore, and means for alternately introducing pressurizedfluid into the ends of said shuttle housing bore to move said shuttleelement between said limit positions in said bore in timed relationshipwith the injection output of said pump to thereby alternately direct thepump output between said first and second fuel injection nozzles.

2. The invention as claimed in claim 1 wherein said means foralternately introducing pressurized fluid into the ends of said shuttlehousing bore includes means for simultaneously draining fluid from theopposite ends of said bore.

3. The invention as claimed in claim 2 wherein said means forintroducing and draining fluid from the ends of said shuttle housingbore comprises distributor means connected by conduit means to the endsof said shuttle housing bore, said distributor means being adapted toalternately connect said latter conduit means to a pressurized fluidsupply and fluid drain sump, said distributor means being connected withsaid pump for synchronized operation therewith.

4. The invention as claimed in claim 1 wherein said shuttle elementcomprises a cylindrical member having a circumferential groove therein,said shuttle element groove being adapted to communicate at all timeswith said fuel delivery passage, said shuttle element groove beingadapted in one limit position of said shuttle element to communicatewith one of said discharge passages to direct fuel from said deliverypassagejthereinto, said shuttle element groove being adapted in theother limit position of said shuttle element to communicate with theother of said discharge passages to direct fuel from said deliverypassage thereinto.

5. The invention as claimed in claim 4 wherein said shuttle elementgroove is adapted to communicate with both said discharge passages whensaid shuttle element is positioned in an intermediate position betweensaid limit positions.

6. The invention as claimed in claim 4 wherein said shuttle elementincludes a circumferential balancing groove adjacent each end of saidcircumferential groove, one of said balancing grooves being adapted tocommunicate with one of said discharge passages when the other of saiddischarge passages is in communication with said circumferential groove.

7. The invention as claimed in claim 1 wherein said means forestablishing limit positions of said shuttle element comprises axiallyspaced inserts in said shuttle housing bore.

8. The invention as claimed in claim 7 including means for snubbing themovement of said shuttle element into the limit positions.

9. The invention as'claimed in claim 8 wherein said snubbing meanscomprises means on said inserts adapted to cooperate with the ends ofsaid shuttle element to trap'fluid therebetween and thereby preventdestructive contact of said shuttle element with said inserts.

10. The invention as claimed in claim 1 wherein said pressurized fluidintroduced into the ends of said shuttle housing bore comprises fuel.

11. The invention as-claimed in claim 10 wherein said means foralternately introducing the pressurized fuel into the ends of saidshuttle housing bore includes means for simultaneously draining fluidfrom the opposite ends of said bore. I

12. The invention as claimed in claim 11 wherein said means forintroducing and draining fuel from the ends of said shuttle housing'borecomprises distributorv meansconnected by conduit means to the ends ofsaid shuttle housing bore, said distributor means being adapted toalternately connect said latter conduit means to a pressurized fuelsupply and fuel drain sump, said distributor means being connected withsaid pump for synchronized operation therewith.

13. The invention as claimed in claim 12 wherein said pressurized fuelsupply comprises the fuel pump fuel supply.

14. The invention as claimed in claim 12 wherein said distributor meanscomprises a rotary distributor driven by said pump.

15. The invention as claimed in claim 11 shuttle element comprises acylindrical member having first and second axially spacedcircumferential grooves therein, said first shuttle groove being adaptedto communicate with said delivery passage and one of said dischargepassages when said shuttle element is in a first limit position, saidsecond shuttle groove being adapted to communicate with said deliverypassage and the ing the idle fuel delivery and discharge passagescomprises an intermediate circumferential groove in said shuttle elementbetween said first and second circumferential grooves, said intermediategroove being adapted to communicate with one of said discharge passageswhen the other of said passages is communicating with one of said firstor second shuttle element grooves in a limit position of said shuttleelement, and means in said shuttle element for connecting saidintermediate groove with the pressurized end of said shuttle housingbore. 1

. 18. The invention as claimed in claim 17 wherein said latter meanscomprises an axial bore in said shuttle, port means connecting saidintermediate shuttle groove with said axial bore, and valve mean forclosing said shuttle bore between said intermediate groove port meansand the drained end of said shuttle housing bore whereby pressurizedfuel passes from the pressurized end of said bore through the shuttlebore, port means and intermediate groove into one of said dischargepassages to fill and maintain an above atmospheric residual fuelpressure in said passage.

' 19. The invention as claimed in claim 18 wherein said intermediategroove is adapted to communicate with said delivery passage as saidshuttle element moves between said limit positions to thereby fill andmaintain a residual pressure in said delivery passage.

20. The invention as claimed in claim 16 wherein said shuttle elementpassage means for filling and pressurizing the idle fuel delivery anddischarge passages comprises a pair of intermediate circumferentialgrooves in said shuttle element between said first and secondshutwherein said other of said discharge passages when said shuttleelement is in a second limit position.

16. The invention as claimed in claim 15 wherein said shuttle elementincludes passage means therein for filling and pressurizing the idlefuel delivery and discharge passages with pressurized fuel from theshuttle housing bore.

17. The invention as claimed in claim 16 wherein said shuttle elementpassage means for filling and pressuriztle element grooves, a boreextending from each end of said shuttle element partway thereint'o,passage means connecting one of said intermediate shuttle elementgrooves with one of said shuttle element bores, passage means connectingthe other of said shuttle element intermediate grooves with the other ofsaid shuttle element bores, said intermediate grooves and shuttleelement bores being disposed and related so that in a first limitposition of the shuttle element one of said intermediate groovescommunicates with the idle discharge passage and connects the passagewith the pressurized end of said shuttle housing bore, and wherein inthe second shuttle element limit position the other of said intermediateshuttle element grooves connects the other of said discharge passageswith the opposite pressurized end of said shuttle housing bore.

21. The invention as claimed in claim 20 wherein said intermediateshuttle element grooves are adapted to communicate with said deliverypassage as said shuttle element moves between said limit positions tothereby fill and maintain a residual pressure in said delivery passage.

22. The invention as claimed in claim 15 including means for relievinginjection pressure should the shuttle element stop betweenlimitpositions with neither the first nor second groove thereof incommunication with said delivery passage.

1. In a fuel injection pump adapted to intermittently supply meteredquantities of high pressure fuel to a first fuel injection nozzle, theimprovement comprising means for alternately directing the intermittentfuel output of said pump into a second nozzle, said means comprising ahydraulic shuttle assembly including a shuttle housing having a boretherein, a shuttle element slidably disposed in said bore, a deliverypassage in said housing for introducing the fuel output of said pumpinto said shuttle housing bore, a pair of fuel discharge passages insaid shuttle housing communicating with said housing bore, saiddischarge passages being adapted for connection to conduit means fordelivering fuel to said first and second fuel injection nozzles, meansfor establishing limit positions of said slidable shuttle element, meanson said shuttle element for providing fluid communication of saiddelivery passage with one of said discharge passages when said shuttleelement is in a first limit position in said bore and for providingfluid communication of said delivery passage with the other of saiddischarge passages when said shuttle element is in a second limitposition in said bore, and means for alternately introducing pressurizedfluid into the ends of said shuttle housing bore to move said shuttleelement between said limit positions in said bore in timed relationshipwith the injection output of said pump to thereby alternately direct thepump output between said first and second fuel injection nozzles.
 2. Theinvention as claimed in claim 1 wherein said means for alternatelyintroducing pressurized fluid into the ends of said shuttle housing boreincludes means for simultaneously draining fluid from the opposite endsof said bore.
 3. The invention as claimed in claim 2 wherein said meansfor introducing and draining fluid from the ends of said shuttle housingbore comprises distributor means connected by conduit means to the endsof said shuttle housing bore, said distributor means being adapted toalternately connect said latter conduit means to a pressurized fluidsupply and fluid drain sump, said distributor means being connected withsaid pump for synchronized operation therewith.
 4. The invention asclaimed in claim 1 wherein said shuttle element comprises a cylindricalmember having a circumferential groove therein, said shuttle elementgroove being adapted to communicate at all times with said fuel deliverypassage, said shuttle element groove being adapted in one limit positionof said shuttle element to communicate with one of said dischargepassages to direct fuel from said delivery passage thereinto, saidshuttle element groove being adapted in the other limit position of saidshuttle element to communicate with the other of said discharge passagesto direct fuel from said delivery passage thereinto.
 5. The invention asclaimed in claim 4 wherein said shuttle element groove is adapted tocommunicate with both said discharge passages when said shuttle elementis positioned in an intermediate position between said limit positions.6. The invention as claimed in claim 4 wherein said shuttle elementincludes a circumferential balancing groove adjacent each end of saidcircumferential groove, one of said balancing grooves being adapted tocommunicate with one of said discharge passages when the other of saiddischarge passages is in communication with said circumferential groove.7. The invention as claimed in claim 1 wherein said means forestablishing limit positions of said shuttle element comprises axiallyspaced inserts in said shuttle housing bore.
 8. The invention as claimedin claim 7 including means for snubbing the movement of said shuttleelement into the limit positions.
 9. The invention as claimed in claim 8wherein said snubbing means comprises means on said inserts adapted tocooperate with the ends of said shuttle element to trap fluidtherebetween and thereby prevent destructive contact of said shuttleelement with said inserts.
 10. The invention as claimed in claim 1wherein said pressurized fluid introduced into the ends of said shuttlehousing bore comprises fuel.
 11. The invention as claimed in claim 10wherein said means for alternately introducing the pressurized fuel intothe ends of said shuttle housing bore includes means for simultaneouslydraining fluid from the opposite ends of said bore.
 12. The invention asclaimed in claim 11 wherein said means for introducing and draining fuelfrom the ends of said shuttle housing bore comprises distributor meansconnected by conduit means to the ends of said shuttle housing bore,said distributor means being adapted to alternately connect said latterconduit means to a pressurized fuel supply and fuel drain sump, saiddistributor means being connected with said pump for synchronizedoperation therewith.
 13. The invention as claimed in claim 12 whereinsaid pressurized fuel supply comprises the fuel pump fuel supply. 14.The invention as claimed in claim 12 wherein said distributor meanscomprises a rotary distributor driven by said pump.
 15. The invention asclaimed in claim 11 wherein said shuttle element comprises a cylindricalmember having first and second axially spaced circumferential groovestherein, said first shuttle groove being adapted to communicate withsaid delivery passage and one of said discharge passages when saidshuttle element is in a first limit position, said second shuttle groovebeing adapted to communicate with said delivery passage and the other ofsaid discharge passages when said shuttle element is in a second limitposition.
 16. The invention as claimed in claim 15 wherein said shuttleelement includes passage means therein for filling and pressurizing theidle fuel delivery and discharge passages with pressurized fuel from theshuttle housing bore.
 17. The invention as claimed in claim 16 whereinsaid shuttle element passage means for filling and pressurizing the idlefuel delivery and discharge passages comprises an intermediatecircumferential groove in said shuttle element between said first andsecond circumferential grooves, said intermediate groove being adaptedto communicate with one of said discharge passages when the other ofsaid passages is communicating with one of said first or second shuttleelement grooves in a limit position of said shuttle element, and meansin said shuttle element for connecting said intermediate groove with thepressurized end of said shuttle housing bore.
 18. The invention asclaimed in claim 17 wherein said latter means comprises an axial bore insaid shuttle, port means connecting said intermediate shuttle groovewith said axial bore, and valve mean for closing said shuttle borebetween said intermediate groove port means and the drained end of saidshuttle housing bore whereby pressurized fuel passes from thepressurized end of said bore through the shuttle bore, port means andintermediate groove into one of said discharge passages to fill andmaintain an above atmospheric residual fuel pressure in said passage.19. The invention as claimed in claim 18 wherein said intermediategroove is adapted to communicate with said delivery passage as saidshuttle element moves between said limit positions to thereby fill andmaintain a residual pressure in said delivery passage.
 20. The inventionas claimed in claim 16 wherein said shuttle element passAge means forfilling and pressurizing the idle fuel delivery and discharge passagescomprises a pair of intermediate circumferential grooves in said shuttleelement between said first and second shuttle element grooves, a boreextending from each end of said shuttle element partway thereinto,passage means connecting one of said intermediate shuttle elementgrooves with one of said shuttle element bores, passage means connectingthe other of said shuttle element intermediate grooves with the other ofsaid shuttle element bores, said intermediate grooves and shuttleelement bores being disposed and related so that in a first limitposition of the shuttle element one of said intermediate groovescommunicates with the idle discharge passage and connects the passagewith the pressurized end of said shuttle housing bore, and wherein inthe second shuttle element limit position the other of said intermediateshuttle element grooves connects the other of said discharge passageswith the opposite pressurized end of said shuttle housing bore.
 21. Theinvention as claimed in claim 20 wherein said intermediate shuttleelement grooves are adapted to communicate with said delivery passage assaid shuttle element moves between said limit positions to thereby filland maintain a residual pressure in said delivery passage.
 22. Theinvention as claimed in claim 15 including means for relieving injectionpressure should the shuttle element stop between limit positions withneither the first nor second groove thereof in communication with saiddelivery passage.